1. Field of the Invention
The present invention relates to cleaning studs or bolts. More particularly, the invention relates to an apparatus for safely and effectively cleaning the studs used to secure reactor heads on nuclear reactors.
2. Description of the Related Art
Nuclear reactor vessels typically have had a reactor head secured to the reactor vessel by large studs or bolts. The reactor studs were very large, typically around 6 feet in length and weighing up to one thousand pounds (1000 lbs.) or more. When the nuclear reactors were shut down at scheduled intervals for maintenance and inspection, the reactor studs had to be removed for cleaning and inspection.
The size and weight of the reactor studs made cleaning of the studs a cumbersome and time consuming process. The cleaning process traditionally involved using an A-frame assembly and a manual chain hoist to move the reactor studs into position for cleaning. The reactor studs were then cleaned by hand using brushes or rags to remove any build up of oxides, residues, or dried lubricants.
There were several problems with this process for cleaning reactor studs. The cleaning process was very laborious and consumed a significant amount of manual labor. In addition, because of the possibility that the reactor studs were somewhat radioactive, personnel could only be exposed to the studs for a short period of time. Another problem with the traditional reactor stud cleaning process was that it created a large amount of waste such as rags, scrubbing pads, and brushes that had to be treated as radioactive waste.
To overcome the problems associated with manual cleaning of the reactor studs, stud cleaning machines were developed such as those disclosed in U.S. Pat. Nos. 4,165,549 and 4,452,753. These machines had housings in which a stud was placed so that the stud's longitudinal axis extended in the horizontal direction. The studs were rotated along the longitudinal axis inside the housings and cleaning was accomplished by the rotating brushes.
There were several problems with these machines. First, the stud had to be positioned in a horizontal plane requiring extra handling of the potentially radioactive stud. Additionally, the machines used a mechanical cleaning process and did not have capability to utilize solvents and other cleaning agents. Further, the machines only had the capability of cleaning one reactor stud at a time.
U.S. Pat. No., 4,630,410 similarly disclosed an apparatus having horizontal housing for cleaning reactor studs. However, in this apparatus, the rotary brushes were replaced with a high pressure spray nozzle that used water and an abrasive to clean the stud. This apparatus shared many of the same problems including requiring additional handling to put the studs in the horizontal position and being limited to cleaning one reactor stud at a time.